<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <title>Title</title>
  <script src="./vue.js"></script>
</head>
<body>
<div id="root">
  <form @click.prevent="fn2" action="http://www.baidu.com">
    <button @click.prevent.once="fn">提交</button>
  </form>
</div>
</body>
<script>
  new Vue({
    el: "#root",
    methods:{
      fn(){
        console.log("fn");
      },
      fn2(){
        console.log("fn2");
      }
    }
  })
</script>
</html>